In-tank fuel pump reservoir assemblies have been employed in automotive engine fuel delivery systems and similar applications to draw fuel from a fuel supply tank and deliver that fuel under pressure to an engine. In-tank fuel pump reservoir assemblies generally include a fuel reservoir canister that is suspended within a fuel supply tank from a mounting plate fastened across an opening in an upper wall or side wall of the fuel supply tank. The canister defines a reservoir chamber for holding a relatively small quantity of fuel. Fuel pump reservoir assemblies of this type also include a reservoir outlet that connects to a fuel line leading to an engine through the mounting plate and a reservoir inlet positioned to provide a one-way fluid path from the supply tank to the reservoir chamber. An electric fuel pump assembly is supported within the reservoir canister and has a fuel pump inlet in fluid communication with the reservoir chamber. The electric fuel pump also has a fuel pump exhaust in fluid communication with the reservoir outlet. The electric fuel pump assembly draws fuel from the reservoir chamber through the fuel pump inlet and delivers at least a portion of that fuel to the engine through the reservoir outlet. An inlet filter is typically disposed between the reservoir chamber and the pump inlet and an outlet filter is typically disposed between the pump exhaust and the reservoir outlet. It is also known for an in-tank fuel pump reservoir assembly to include a reservoir filling device such as a jet pump or venturi that is supported within the reservoir canister in fluid communication with the reservoir inlet. The reservoir-filling device would be included to draw fuel into the reservoir chamber from the fuel supply tank through the reservoir inlet and an inlet check valve. An inlet check valve, or "foot valve", is included to prevent fuel from exiting the reservoir chamber through the reservoir inlet. An outlet check valve prevents fuel from back flowing through the electric fuel pump and into reservoir chamber. Some in-tank fuel pump reservoir assemblies also include a fuel pressure regulator supported within the reservoir in fluid communication with the fuel pump exhaust and the reservoir outlet. The fuel pressure regulator is configured to limit reservoir assembly output pressure by metering a portion of high-pressure fuel from the fuel pump exhaust back to the reservoir or the supply tank. In-tank fuel pump reservoir assemblies must be modified to accommodate various output and configuration requirements peculiar to different vehicle applications. This generally requires extensive retooling to provide a compatible for each separate application.
The electric fuel pumps used in in-tank fuel pump reservoir assemblies may be of the electric motor regenerative type that typically include housings adapted to be immersed in fuel typically in a supply tank with an inlet for drawing liquid fuel from a surrounding tank and an outlet for feeding fuel under pressure to the engine. The electric motor powering such a pump includes a rotor mounted for rotation within the housing and connected to a source of electrical power for driving the rotor for rotation about its axis. An impeller is coupled to the rotor for co-rotation with the rotor and has a circumferential array of vanes about the periphery of the impeller. An arcuate pumping channel with an inlet port and an outlet port at opposed ends of the channel surrounds the impeller periphery for developing fuel pressure through a vortex like action on the liquid fuel between pockets formed by the impeller vanes and the surrounding channel.
One example of a fuel pump of this type is illustrated in U.S. Pat. No. 5,257,916. In fuel pumps of this type, the outlet port of the pumping channel discharges into a chamber of the fuel pump housing containing the electric motor to cool the electric motor as the fuel flows past the motor and out of the outlet of the housing to supply fuel under pressure to an operating engine. While generally effective at cooling the electric motor, pumps of this type have the disadvantage of heating the fuel. Another disadvantage of fuel pumps of this type is the resistance they provide to the flow of fluid being pumped through the electric motor portion of the pump. This resistance limits the efficiency of such pumps.